Rebuild: Base size, mecanums vs omnis, length, and tips :)

Hello Everyone! I am planning a rebuild and I have a couple questions. First of all, I like mecanums better, but have been told that they are not very good. My questions is, for base width, mecanums or omnis? I would prefer mecanums, so keep that in mind. The second question which relates to the first, is how wide my base needs to be for me to comfortably stack two in the protected zone? (holes are 0.5") Also, from complex tray experience, should I direct drive or use a gearing ratio for the front wheels(spacewise)?

  • Direct Drive
  • Gearing Ratio

0 voters

I was also wondering a good length for the base because all around I have heard 2 different things, a shorter or longer base.

  • Shorter (15" or shorter)
  • Longer(16" or longer)

0 voters

Lastly, I would like to request tips on complex traybots that you have figured out. Thank you for your time!

What tips I know

HS axles on arms, brace towers better(I need suggestions on what techniques to use for this), better bracing on intake arms(x and/or 1x5 brace), and screw joints

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Hey, your polls don’t seem to be working rn
Edit: autocorrect sucks
Edit: it sucked again

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you mean polls, right? :joy:
(you managed to change it from “pills” to “pollss” :laughing:)

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Polls fixed, thank you!

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Mecanum wheels are great in concept, but in VRC they don’t really work. They are better suited for larger, heavier robots. That is why they are common in FRC, and uncommon here. Mecanum wheels suffer from a few disadvantages over Omin-Wheels in VRC, but the biggest one I’ve encountered in my tests was issues with turning. I was unable to get them to turn smoothly without a very heavy robot.

Length will be up to you, and what you value more. Longer robots will be more stable, but harder to control than shorter ones. Longer robots can also hold more cubes. Keep in mind that many tray bots need anti-tips, even, with a long chaises.

Since this game has pretty heavy defense, a 4 motor direct drive will almost always be better than geared. It gives you less moving parts that could fail, such as gears snapping.

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Thing to note: I like strafing in this game, but I should be able to approach cubes at any angle with less compression than 4in and better bracing, so that might make up for it.

Also, how wide of a base do I need for it to be able to stack 2 in there comfortable, because mecanums are wide bois.

ANYWAYS, I don’t know who keeps saying mecanums are bad, but i have experience with them, and they are beasts. Their strafing ability has come in handy nearly every time I drive, and they are very accurate. they also resist defense the best out of all the wheels, since they take up the most surface area. The only cons I see with them is the fact that they are slow in turning. I recommend mecanums. For the base, the only real reason you would need to chain them/do a geared drivetrain is if you wanted to speed up/slow down the base or if you needed your motors out of the way for something. so unless you need to gear your drivetrain, I would recommend to not. the gears/chain creates give in the wheels when they turn, which is a factor that could make programming more difficult. those are my thoughts.

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for the base, you can make it really anywhere from 24 to 29 holes wide. no leeks :eyes: but my base is within that range, and it does stack 2 comfortably.

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7K would like to know your location.

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The number I’ve been hearing allot is 27 holes or 13.5”. I have a 25 hole or 12.5” wide chassis and it seems pretty tight to me. I’d recommend no larger than 25 holes wide.
Edit: I’ve had experience with Mecanums before and I love them. Just make sure your robot has decent enough balance so the traction on the front is somewhat equal to the back or you’ll strafe in circles. I also recommend a lighter bot because they don’t turn quite as nice as omnis, but I do recommend Mecanums.

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Thank you everyone for your help so far! I have decided I am going to go for a 12.5"(ish) base, and direct driven motors. I will go for mecanums(if I can fit them) as well.

The poll for length seems to be tight, so I am wondering why you choose your option and the reasoning behind it.

Lastly, I dont have too long to build (comp is on 25th), so I would love some tips on a 1x2 or 1x3 base(and which one you prefer), as well as bracing and where to attach the towers. The reason I am rebuilding is because my base and bracing was bad, and I need to improve that. Thank you for the feedback so far!

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If you really want to strafe, an x drive is an option. The tricky part about x drives is getting your front wheels to fit without widening your base too much.

If you angled your omnis straighter than 45 degrees, that might be good. They’ll take up less room, and you’ll push stronger. I have no idea how well strafing would work with an x drive like that though, I’ve never actually seen it done. Just an idea.

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I just want to mention that teams do not really use mecanums to help pick up cubes, but instead, they use them for towers and depositing cubes in the zones. They also help out in autonomous.

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  1. Direct driving motors gives quick, instant power with no slack or extra friction. Motors should be able to fit behind your tray (I dont know why they wouldnt?)

  2. 25 to 30 hole bases allow you to go into the large zone parallel with the wall for easy scoring.

  3. Mecanums can be used if you want, just keep in mind they’re a bit larger than omnis. Camt really speak on their effectivieness as I’ve never used them

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Yeah I noticed last year you can be really precise in auton with encoders if you have Mecanums considering they stop on a dime.

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Hello again! I have a few requests for those who are knowledgeable in the areas where I need help. First off, I im not very good at bases and I am wondering if anyone has a CAD(or can help me) for 1x2 or 1x3 bases that are not very wide. I plan to use mecanums if they can fit, and I am wondering if ~8.5 inches of space is viable to use(since mecanums are 2in wide) is enough space to make a sturdy robot.

My last request is tips on bracing like what types of bracing, how I should connect towers to base for maximum sturdiness possible, etc. Thank you!

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A longer base can be better but so can a shorter base. Smaller wheels give a lower center of gravity making your robot more stable.

If you want to build a tray bot, it is probably best if you lower the center of gravity when you want to extend the ramp. This is for more balance.

make a medium length base. like 27-30 holes. that way you can mount your intakes in such a way that they won’t require a deploy. makes things so much simpler.

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Ok everyone. Based on feedback, I am going to go with a ~12.5" wide base, a shorter in length base ~11-13 inches(to fit rollers, is that too much? (Those without flipouts like 1961z, how long are your bases? The diagonals make it hard for me to count) as well as direct drive, and mecanums if they fit.

Two things I would like to request is how to attach towers and brace them well (triangle brace is the only one I know of, and building up for the sides. Those of you with complex traybots, in what ways do you brace your towers reliably so they do not move at all or very little?

Secondly, I would like to ask how you make 1x2 bases sturdy at the back. I get bridges across the middle, but how do you keep the two wheel parts together?

Thank you for the feedback so far!

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